The displayed formula of a fuel molecule is shown. When this fuel is burned in a plentiful supply of oxygen it undergoes complete combustion. Which pair of ...
Question 1 Report
The displayed formula of a fuel molecule is shown. When this fuel is burned in a plentiful supply of oxygen it undergoes complete combustion. Which pair of substances is produced?
Answer Details
Read the displayed formula first. One carbon atom is joined by four single bonds to four hydrogen atoms, so the fuel is methane, CH4. In complete combustion every carbon atom is fully oxidised to carbon dioxide and every hydrogen atom ends up in water: CH4 + 2O2 → CO2 + 2H2O. The products are therefore carbon dioxide and water.
Carbon and carbon monoxide are products of incomplete combustion, which happens only when oxygen is limited, and the question states a plentiful supply. Hydrogen is never a combustion product, because the hydrogen atoms are what react with oxygen to make the water. Any hydrocarbon burned in excess oxygen gives the same two products.
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